Elimination of polymer fouling in fluidized bed gas-phase fines recovery eductors

ABSTRACT

An eductor, a process and apparatus for gas phase polymerization of olefins in a polymerization reactor are disclosed. The process and apparatus employ an eductor which has an inlet which makes a bend of less than about 90° toward the outlet after entering the mixing chamber of the eductor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. ProvisionalApplication No. 62/408,421, entitled “Elimination of PolymerizationFouling in Fluidized Bed Gas-Phase Fines Recovery Eductors,” filed onOct. 14, 2016, the entirety of which is hereby incorporated herein byreference.

FIELD OF THE DISCLOSURE

This disclosure relates generally to eductors and their design, andmethods and apparatuses for using the same.

BACKGROUND

Gas phase polymerization processes typically produce a gaseous streamexiting the gas phase reactor that contains fine solid particles,unreacted olefins, and other gaseous and particulate components. Thesefine solid particles are often referred to as polymer fines, and theyinclude growing polymer particles, formed and agglomerated polymerparticles, and catalyst or pre-polymer particles. In gas phase,fluidized bed polymerization processes, it is desirable to separatethese solid fines from the exit gases and return them to the gas-phasereactor for further reaction.

Eductors are frequently used in the separation and return of the solidfines to the reactor. In commercial polymerization processes, forexample continuous gas-phase, fluidized bed polyolefin polymerizationprocesses, eductors may be used in combination with fines separatorssuch as cyclones in this process. For example, the solid fines particlescan be removed from the bottom of the cyclone by the suction provided byan ejector and recycled to the reactor. However, with typical eductordesigns, it is common that the gas loop piping and equipment will foulwith polymer build up in low-flow zones. Build-up may arise from thedeposition of formed polymer particles or growing polymer particles thatmay continue polymerization of available olefins. The extent of thisproblem may be sufficiently severe that a shutdown is periodicallyrequired for cleaning, in some instances as often as every few months.Such incidents are costly from both time and economic standpoints.Eductors can provide the motive force necessary to transfer the streamcomprising fine particles back into the reactor.

Various solutions to the problem of eductor fouling have been proposed.For example, the eductor may periodically be flushed with a nitrogenpurge or a continuous motive gas purge, whereby the cyclone and eductorare purged with a stream of high pressure gas, to remove any collectedfines and prevent further eductor fouling. However, eductor purges causedown time in the reactor and eductor operations, resulting in extremelyhigh operating and maintenance costs. Various eductor designs have alsobeen explored in an attempt to address this issue and improve metricssuch as reactor run time from a mechanical solution standpoint.

Therefore, there is an ongoing need for improved eductor designs whichmight reduce the incidence of polymer fouling. There is also a need fornew eductor designs which do not require frequent high pressure nitrogenor liquid purges, and which may thereby increase efficiency andprofitability of the reactor systems with which they are associated.

SUMMARY

According to the present disclosure, an eductor is provided having astructure that improves the operation and efficiency of the eductor, andwhich addresses the polymer fouling problem. Therefore, this disclosureprovides an eductor comprising:

a first tubular body having a hollow interior and comprising

-   -   a first inlet and a first outlet spaced apart from the first        inlet along a central axis, and    -   a sidewall circumscribing the central axis and defining a mixing        chamber;

a second tubular body having a hollow interior and comprising a secondinlet and a spaced apart second outlet which extends into the mixingchamber through the sidewall of the first tubular body between the firstinlet and the first outlet; and

wherein the second inlet is oriented substantially perpendicular to theaxis of the first tubular body;

wherein the second tubular body comprises a first bend of less than 90°from perpendicular toward the first outlet before extending into themixing chamber; and

wherein the second tubular body comprises a second bend of less than 90°toward the first outlet after extending into the mixing chamber.

As an example, the second tubular body can make a first bend of about45° from perpendicular toward the first outlet before entering themixing chamber and make a second bend of about 45° toward the firstoutlet after entering the mixing chamber.

In accordance with a further aspect, this disclosure provides an eductorcomprising:

a first tubular body having a hollow interior and comprising

-   -   a first inlet and a first outlet spaced apart from the first        inlet along a central axis, and    -   a sidewall circumscribing the central axis and defining a mixing        chamber; and

a second tubular body having a hollow interior and comprising a secondinlet and a spaced apart second outlet which extends into the mixingchamber through the sidewall of the first tubular body between the firstinlet and the first outlet;

wherein the second tubular body comprises a bend of less than 90° towardthe first outlet after extending into the mixing chamber.

In still a further aspect, this disclosure provides an eductorcomprising:

a first tubular body having a hollow interior and comprising

-   -   a first inlet and a first outlet spaced apart from the first        inlet along a central axis, and    -   a sidewall circumscribing the central axis and defining a mixing        chamber; and

a second tubular body having a hollow interior and comprising a secondinlet and a spaced apart second outlet which extends into the mixingchamber through the sidewall of the first tubular body between the firstinlet and the first outlet;

wherein the second inlet is oriented at an angle less than perpendicularto the axis of the first tubular body toward the first outlet beforeextending into the mixing chamber; and

wherein the second tubular body comprises a bend at an angle less thanperpendicular toward the first outlet after extending into the mixingchamber.

Yet a further aspect of this disclosure provides a method of motivatinga gas stream containing solid fines, the method comprising the steps ofintroducing a gas stream comprising solid fines and a gas streamcomprising a motive gas into any of the eductors disclosed herein, suchas those described in the paragraphs above.

Further, this disclosure sets out an apparatus for polymerizing olefins,comprising:

a polymerization reactor for contacting one or more olefins with acatalyst under polymerization conditions to form a gas stream comprisingsolid fines and unreacted olefins;

a fines separator in fluid communication with the polymerization reactorfor separating the solid fines from the unreacted olefins; and

an eductor in fluid communication with the fines separator for conveyingthe solid fines back to the polymerization reactor, wherein the eductoris any eductor disclosed herein, such as one of the eductors describedin the paragraphs above.

This disclosure also sets out a process for polymerizing olefinscomprising:

contacting one or more olefins with a catalyst in a polymerizationreactor under polymerization conditions to form a gas stream comprisingfine polymer particles and unreacted olefins;

passing the gas stream to a fines separator to separate the fine polymerparticles from the unreacted olefins;

passing the fine polymer particles from the fines separator to any ofthe eductors disclosed herein, such as one of the eductors described inthe paragraphs above; and

introducing a motive gas into the eductor to convey the fine polymerparticles back to the polymerization reactor.

These and various other aspects and embodiments of this disclosure areillustrated in the drawings, examples, and detailed description thatfollow.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

The following figures form part of the present specification and areincluded to further demonstrate certain aspects of the presentdisclosure. The invention may be better understood by reference to oneor more of these figures in combination with the detailed description ofspecific aspects presented herein.

FIG. 1 illustrates an exemplary schematic diagram of a gas phase eductorthat includes various conventional design elements.

FIG. 2 illustrates an exemplary schematic diagram illustrating thecomputational fluid dynamics model of the eductor of FIG. 1, where thecolor of the arrows indicates the velocity magnitude of the flowaccording to the color scale illustrated in the figure (u is velocitymagnitude).

FIG. 3 illustrates an exemplary schematic diagram of an eductoraccording to an aspect of the present disclosure.

FIG. 4 illustrates an exemplary schematic diagram illustrating thecomputational fluid dynamics model of the eductor of FIG. 3, where thecolor and direction of the arrows indicate the velocity magnitude of theflow according to the color scale illustrated in the figure (u isvelocity magnitude).

FIG. 5 illustrates an exemplary schematic diagram of a process andapparatus for polymerizing olefins using the eductor of FIG. 3.

FIG. 6 is one illustration of a converging-diverging nozzle which can besituated adjacent to the first outlet. Such a converging (inlet) nozzleand diverging (outlet) diffuser (“converging-diverging nozzle”) uses thepressure energy of a motive gas to create a low pressure zone to suctionand entrain another fluid.

While the inventions disclosed herein are susceptible to variousmodifications and alternative forms, only a few specific embodimentshave been shown by way of example in the drawings and are described indetail below. The figures and detailed descriptions of these specificembodiments are not intended to limit the breadth or scope of theinventive concepts or the appended claims in any manner. Rather, thefigures and detailed written descriptions are provided to illustrate theinventive concepts to a person of ordinary skill in the art and toenable such person to make and use the inventive concepts.

Definitions

The following definitions are provided in order to aid those skilled inthe art in understanding the detailed description of the presentinvention. Unless otherwise defined herein, scientific and technicalterms used in connection with the present invention shall have themeanings that are commonly understood by those of ordinary skill in theart to which this invention belongs, and unless otherwise indicated orthe context requires otherwise, these definitions are applicablethroughout this disclosure. Further, unless otherwise required bycontext, singular terms shall include pluralities and plural terms shallinclude the singular.

If a term is used in this disclosure but is not specifically definedherein, the definition from the IUPAC Compendium of ChemicalTerminology, 2nd Ed (1997) can be applied, as long as that definitiondoes not conflict with any other disclosure or definition appliedherein, or render indefinite or non-enabled any claim to which thatdefinition is applied. To the extent that any definition or usageprovided by any document incorporated herein by reference conflicts withthe definition or usage provided herein, the definition or usageprovided herein controls.

Unless explicitly stated otherwise in defined circumstances, allpercentages, parts, ratios, and like amounts used herein are defined byweight.

Further, in this connection, certain features of the invention whichare, for clarity, described herein in the context of separateembodiments, may also be provided in combination in a single embodiment.Conversely, various features of the invention that are, for brevity,described in the context of a single embodiment, may also be providedseparately or in any sub-combination.

Regarding claim transitional terms or phrases, the transitional term“comprising”, which is synonymous with “including”, “containing”, or“characterized by” is inclusive or open-ended and does not excludeadditional, un-recited elements or method steps. The transitional phrase“consisting of” excludes any element, step, or ingredient not specifiedin the claim. The transitional phrase “consisting essentially of” limitsthe scope of a claim to the specified materials or steps and those thatdo not materially affect the basic and novel characteristic(s) of theclaimed invention. A “consisting essentially of” claim occupies a middleground between closed claims that are written in a “consisting of”format and fully open claims that are drafted in a “comprising” format.Absent an indication to the contrary, when describing a compound orcomposition “consisting essentially of” is not to be construed as“comprising,” but is intended to describe the recited component thatincludes materials which do not significantly alter composition ormethod to which the term is applied. For example, a feedstock consistingessentially of a material A can include impurities typically present ina commercially produced or commercially available sample of the recitedcompound or composition. When a claim includes different features and/orfeature classes (for example, a method step, feedstock features, and/orproduct features, among other possibilities), the transitional termscomprising, consisting essentially of, and consisting of, apply only tofeature class to which is utilized and it is possible to have differenttransitional terms or phrases utilized with different features within aclaim. For example, a method can comprise several recited steps (andother non-recited steps) but utilize a catalyst system preparationconsisting of specific steps and utilize a catalyst system comprisingrecited components and other non-recited components. While compositionsand methods are described in terms of “comprising” various components orsteps, the compositions and methods can also “consist essentially of” or“consist of” the various components or steps.

The articles “a” and “an” may be employed in connection with variouselements and components of compositions, processes or structuresdescribed herein. This is merely for convenience and to give a generalsense of the compositions, processes or structures. Such a descriptionincludes “one or at least one” of the elements or components. Moreover,as used herein, the singular articles also include a description of aplurality of elements or components, unless it is apparent from aspecific context that the plural is excluded.

“Optional” or “optionally” means that the subsequently described eventor circumstance can or cannot occur, and that the description includesinstances where the event or circumstance occurs and instances where itdoes not.

The terms “configured for use” or “adapted for use” and similar languageis used herein to reflect that the particular recited structure orprocedure is used in an olefin polymerization system or process asdisclosed herein. For example, unless otherwise specified, a particularstructure “configured for use” means it is “configured for use in anolefin polymerization reactor system” and therefore is designed, shaped,arranged, constructed, and/or tailored to effect an olefinpolymerization, as would have been understood by the skilled person.

Terms such as “eductor”, “ejector”, “eductor pump”, “ejector pump”,“aspirator” and similar terms are used interchangeably to refer todevices that use the Venturi effect of a converging nozzle to convertthe pressure energy of a motive fluid, in this case a motive gas, tocreate a low pressure zone to suction and entrain another fluid. Typicaleductors use a converging (inlet) nozzle and diverging (outlet) diffuser(“converging-diverging nozzle”) and the pressure energy of a motivefluid, typically a motive gas, to create a low pressure zone to suctionand entrain another fluid. As used herein, a “motive gas” is a gas whichis used to entrain polymer fines by imparting suction to the eductor bycreating a low pressure area at the discharge of a nozzle and/ordownstream of a constricted area. The reduction in fluid pressureresults when a fluid flows through a section of a pipe that firstnarrows or constricts to a smaller cross section and then enlarges to alarger cross section. The term “converging-diverging nozzle” refers tothe portion of the eductor that includes the converging (inlet) nozzleand diverging (outlet) diffuser. Other portions of the eductor relate tohow the motive fluid and the other fluid to be entrained enter and/orare mixed in the eductor.

The term “fines”, “solid fines”, “polymer fines”, “solid polymer fines”and the like are used interchangeably herein to refer to solid particleswhich have an average particle size of less than the median particlesize of the solid particles in the relevant gaseous stream comprisingsuch particles. In one aspect, solid fines can have an aerodynamicdiameter of about or less than 2.5 μm (microns) (also referred to asPM_(2.5)), 5 microns, 10 microns, 20 microns, 50 microns, 75 microns, or200 mesh. Even though the term “polymer” may be associated with the term“fines”, this term is intended to encompass any solid particle in thesubject gaseous stream, including catalyst or pre-polymer particles thatmay be charged to the reactor, growing polymer particles, agglomeratedpolymer particles, and the flakes or spalling of polymer particles. Insome embodiments, the polymer particle size in the process can includebut is not limited to the following sizes; Group A, 30 to 100 microns;Group B, 100 to 1,000 microns; Group C, 0 to 30 microns. The polymershould not be construed to be limited to any particular particle sizedistribution.

The term “olefin” is used herein in accordance with the definitionspecified by IUPAC: acyclic and cyclic hydrocarbons having one or morecarbon-carbon double bonds apart from the formal ones in aromaticcompounds. The class “olefins” subsumes alkenes and cycloalkenes and thecorresponding polyenes. Ethylene, propylene, 1-butene, 2-butene,1-hexene and the like are non-limiting examples of olefins. The term“alpha olefin” (α-olefin) refers to an olefin that has a double bondbetween the first and second carbon atom of the longest contiguous chainof carbon atoms. The term “alpha olefin” includes linear and branchedalpha olefins unless expressly stated otherwise.

When describing a range of measurements such as angles and the like, itis the Applicant's intent to disclose every individual number that sucha range could reasonably encompass, for example, every individual numberthat has at least one more significant figure than in the disclosed endpoints of the range. As an example, when referring to an angle of thefirst or the second bend as between 40° and 50°, it is intended todisclose that the angle can be 40°, 41°, 42°, 43°, 44°, 45°, 46°, 47°,48°, 49°, or 50°, including any subranges or combinations of subrangesencompassed in this broader range. Applicant's intent is that these twomethods of describing the range are interchangeable. Moreover, when arange of values is disclosed or claimed, Applicant also intends for thedisclosure of a range to reflect, and be interchangeable with,disclosing any and all sub-ranges and combinations of sub-rangesencompassed therein. Accordingly, Applicant reserves the right toproviso out or exclude any individual members of any such group,including any sub-ranges or combinations of sub-ranges within the group,or any selection, feature, range, element, or aspect that can beclaimed, if for any reason Applicant chooses to claim less than the fullmeasure of the disclosure, for example, to account for a reference thatApplicant may be unaware of at the time of the filing of theapplication. In addition, the ranges set forth herein include theirendpoints unless expressly stated otherwise. Further, when an amount,concentration, or other value or parameter is given as a range, one ormore preferred ranges or a list of upper preferable values and lowerpreferable values, this is to be understood as specifically disclosingall ranges formed from any pair of any upper range limit or preferredvalue and any lower range limit or preferred value, regardless ofwhether such pairs are separately disclosed. The scope of the inventionis not limited to the specific values recited when defining a range.

The term “about” means that amounts, sizes, formulations, parameters,and other quantities and characteristics are not and need not be exact,but may be approximate and/or larger or smaller, as desired, reflectingtolerances, conversion factors, rounding off, measurement error and thelike, and other factors known to those of skill in the art. In general,an amount, size, formulation, parameter or other quantity orcharacteristic is “about” or “approximate” whether or not expresslystated to be such. The term “about” also encompasses amounts that differdue to different equilibrium conditions for a composition resulting froma particular initial mixture. Whether or not modified by the term“about”, the claims include equivalents to the quantities. The term“about” may mean within 10% of the reported numerical value, or within5% of the reported numerical value, or within 2% of the reportednumerical value.

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having,” “contains” or “containing,” or any othervariation thereof, are intended to cover a non-exclusive inclusion. Forexample, a composition, a mixture, process, method, article, orapparatus that comprises a list of elements is not necessarily limitedto only those elements but may include other elements not expresslylisted or inherent to such composition, mixture, process, method,article, or apparatus. Further, unless expressly stated to the contrary,“or” refers to an inclusive or and not to an exclusive or. For example,a condition A or B is satisfied by any one of the following: A is true(or present) and B is false (or not present), A is false (or notpresent) and B is true (or present), and both A and B are true (orpresent).

The term “contacting”, as used herein, refers to the process of bringinginto contact at least two distinct species such that they can react. Itwill be appreciated, however, that the resulting reaction product can beproduced directly from a reaction between the added reagents or from anintermediate from one or more of the added reagents which can beproduced in the reaction mixture.

The terms “substantial” and “substantially”, as used herein, are broadterms, are meant to be given their ordinary and customary meaning to aperson of ordinary skill in the art (and are not to be limited to aspecial or customized meaning), including, without limitation, referringto an amount about 90 degrees from perpendicular, about 85 degrees fromperpendicular, or about 75 degrees from perpendicular, referring to anamount 0 degrees from parallel, 5 degrees from parallel, or 15 degreesfrom parallel.

DETAILED DESCRIPTION

The Figures described above and the written description of specificstructures and functions below are not presented to limit the scope ofwhat Applicants have invented or the scope of the appended claims.Rather, the Figures and written description are provided to teach anyperson skilled in the art to make and use the inventions for whichpatent protection is sought. Those skilled in the art will appreciatethat not all features of a commercial embodiment of the inventions aredescribed or shown for the sake of clarity and understanding. Persons ofskill in this art will also appreciate that the development of an actualcommercial embodiment incorporating aspects of the present inventionswill require numerous implementation-specific decisions to achieve thedeveloper's ultimate goal for the commercial embodiment. Suchimplementation-specific decisions may include, and likely are notlimited to, compliance with system-related, business-related,government-related and other constraints, which may vary by specificimplementation, location and from time to time. While a developer'sefforts might be complex and time-consuming in an absolute sense, suchefforts would be, nevertheless, a routine undertaking for those of skillin this art having benefit of this disclosure. It must be understoodthat the inventions disclosed and taught herein are susceptible tonumerous and various modifications and alternative forms. Lastly, theuse of a singular term, such as, but not limited to, “a,” is notintended as limiting of the number of items. Also, the use of relationalterms, such as, but not limited to, “top,” “bottom,” “left,” “right,”“upper,” “lower,” “down,” “up,” “side,” and the like are used in thewritten description for clarity in specific reference to the Figures andare not intended to limit the scope of the invention or the appendedclaims.

Among other things, this disclosure provides an eductor having animproved operation and efficiency, which reduces the polymer foulingproblem that is typically associated with conventional eductors.Eductors are frequently used to entrain fine solids in a stream offluid, for example, in a polymerization reactor apparatus and processwhere they entrain fine solids in a stream of fluid for recycling backto the polymerization reactor. In some aspects, eductors may be coupledto the solids outlet of a cyclone separator located downstream of apolymerization reactor, wherein the cyclone is used to separate polymerfines from a gas. In the eductors disclosed herein, the eductors may beused to entrain the separated polymer fines in a stream of motive gas,which may comprise unreacted olefins and other hydrocarbons. One aspectinvolves return of the separated polymer fines and/or the unreactedolefins to the gas-phase polymerization reactor.

According to an aspect, this disclosure provides an eductor comprising:a first tubular body having a hollow interior and comprising a firstinlet and a first outlet spaced apart from the first inlet along acentral axis, and a sidewall circumscribing the central axis anddefining a mixing chamber; and a second tubular body having a hollowinterior and comprising a second inlet and a spaced apart second outletwhich extends into the mixing chamber through the sidewall of the firsttubular body between the first inlet and the first outlet; and whereinthe second tubular body comprises a bend of less than 90° toward thefirst outlet after extending into the mixing chamber.

In some aspects and embodiments of this eductor: [1] the second inletcan be oriented at an angle less than perpendicular to the axis of thefirst tubular body toward the first outlet before extending into themixing chamber, and the second tubular body comprises a bend at an angleless than perpendicular toward the first outlet after extending into themixing chamber; or [2] the second inlet can be oriented substantiallyperpendicular to the axis of the first tubular body, wherein the secondtubular body comprises a first bend of less than 90° from perpendiculartoward the first outlet before extending into the mixing chamber, andwherein the second tubular body comprises a second bend of less than 90°toward the first outlet after extending into the mixing chamber.

In a further aspect, this disclosure provides an eductor wherein thesecond tubular body can include a first bend of less than 90° fromperpendicular toward the first outlet before extending into the mixingchamber. In this aspect, the first bend can be about 5°, about 10°,about 15°, about 20°, about 25°, about 30°, about 35°, about 40°, about45°, about 50°, about 55°, about 60°, about 65°, about 70°, about 75°,about 80°, about 85°, or less than 90°, from perpendicular toward thefirst outlet before extending into the mixing chamber, including anyranges between the angles. In yet another aspect, the second tubularbody can include a second bend of less than 90° toward, or in thedirection of, the first outlet after extending into the mixing chamber.In this aspect, the second bend can be about 5°, about 10°, about 15°,about 20°, about 25°, about 30°, about 35°, about 40°, about 45°, about50°, about 55°, about 60°, about 65°, about 70°, about 75°, about 80°,about 85°, or less than 90° toward the first outlet after extending intothe mixing chamber, including any ranges between the angles. As anexample, the first or the second bend as disclosed herein can be betweenabout 30° and about 60°, between about 35° and about 55°, or betweenabout 40° and about 50°.

Many conventional eductors are prone to fouling, whereby solid finescollect in the mixing chamber of the eductor and, over time, partiallyor completely clog and block (partially or fully) the passage of finesthrough the eductor. For example, FIG. 1 depicts a schematic diagram ofa typical gas phase eductor (equivalently referred to as an ejector)that includes various conventional design elements. As shown in thisfigure, cyclones 101 are coupled to eductor 103. As would be understoodby one skilled in the art, fines separated from the cyclones 101 flowdownward as shown by arrow 105 into the eductor, wherein they are forcedto make a 90° turn, and a motive gas flows straight from left to right(as oriented in FIG. 1) into the eductor as shown by arrow 107. However,operation of these eductors in gas-phase polymerization rectors hasrevealed areas which are prone to fouling or plugging with fines, shownas areas 109. Moreover, the fouling of these eductors often results insignificant problems with other connected equipment, for example withdownstream heat exchangers, compressors, and even with reactors whichmay experience fouling, clogging, and/or reduced efficiency.

This fouling or plugging is further illustrated by reference to FIG. 2,which depicts a computational fluid dynamics (CFD) simulation model ofthe eductor of FIG. 1. FIG. 2 depicts a stream of fines from a cyclone205 which are introduced through the top of the eductor 203 (as shown inthis figure) and a stream of motive gas 207 which is introduced throughthe left side of the eductor 203 (as oriented in FIG. 2). Arrows withinthe eductor 203 indicate the direction of flow, while the color of thearrows indicates the velocity of the flow, according to the color scaleillustrated in the figure. As can be seen by reference to this figure,the design of eductor 203 results in two low flow areas 209, whichcorrespond with the areas which are prone to fouling or plugging withfines, shown as area 109 in FIG. 1. As would be appreciated by theskilled person, fines are likely to collect in these low flow areas,because polymer fines are more likely to separate from a stream ofmotive gas as the flow rate of that motive gas decreases, resulting overtime in eductor fouling and/or clogging, and plant downtime.

FIG. 3 depicts a schematic diagram of an eductor 301 according to anembodiment of the present disclosure. In this embodiment, the eductor301 has a first tubular body 302 having a hollow interior, which has afirst inlet 303, and a first outlet 305 spaced apart from the firstinlet 303, both of which are along a central axis A. The eductor 301further has a sidewall 307 circumscribing the central axis A anddefining a mixing chamber 309 within. Additionally, the eductor 301 hasa second tubular body 311, which has a second inlet 313 and a secondoutlet 315 spaced apart from the second inlet 313. As can be seen inFIG. 3, the second tubular body 311 extends into the mixing chamber 309through the sidewall 307 of the first tubular body 302. In theembodiment illustrated in FIG. 3, the second tubular body 311 has twoseparate 45° bends, a first bend which occurs outside the first tubularbody 302 between the second inlet 313 and the second outlet 315, priorto the tubular body 302 entering and passing through sidewall 307 intothe mixing chamber 309, and a second turn which occurs inside the mixingchamber 309 between the second inlet 313 and the second outlet 315. Morespecifically, in the embodiment illustrated in FIG. 3, the secondtubular body 311 has a second turn which occurs inside the mixingchamber 309 between the second inlet 313 and the second outlet 315, suchthat the second outlet 315 is coaxial with the central axis A. In someembodiments of this eductor design, the second inlet 313 can be orientedat an angle less than perpendicular to the axis of the first tubularbody 302 toward the first outlet 305 before extending into the mixingchamber, and the second tubular body comprises a bend at an angle lessthan perpendicular toward the first outlet after extending into themixing chamber.

In some embodiments, the second inlet 313 may be oriented substantiallyperpendicular to the central axis A of the first tubular body 302. Insome embodiments, the second tubular body 311 may have a first bend ofless than about 90° from perpendicular toward the first outlet 305before extending into the mixing chamber 309 between the second inlet313 and the second outlet 315 and may also have a second bend of lessthan about 90° toward the first outlet 305 after extending into themixing chamber 309 between the second inlet 313 and the second outlet315. In some embodiments, the first inlet 303 is in fluid communicationwith the fines outlet of a cyclone separator, such that a stream offines passes through the first inlet 303, and a stream of a motive gaspasses through the second inlet 313. In accordance with some otherembodiments of the disclosure, the second inlet 313 is in fluidcommunication with the fines outlet of a cyclone separator, such that astream of fines passes through the second inlet 313, and a stream of amotive gas passes through the first inlet 303. While illustrated suchthat the central axis A is substantially vertical, in some embodimentsof the present disclosure, the eductor may be used in otherconfigurations. For example, in some embodiments of the presentdisclosure, the eductor 301 can be configured such that the central axisA can be substantially horizontal, or can be at any angle between about0° and about 90° from horizontal, for example and without limitation,about 15° from horizontal, about 30° from horizontal, about 45° fromhorizontal, about 60° from horizontal, about 75° from horizontal, orabout 90° from horizontal.

In some embodiments of the present disclosure, the second tubular body311 may be substantially parallel to the central axis A at the secondoutlet 315. In some embodiments of the present disclosure, the secondtubular body 311 may be coaxial with the first tubular body 302 aboutthe central axis A at the second outlet 315. However, in someembodiments of the present disclosure, the second tubular body 311 maynot be coaxial with the first tubular body 302 about the central axis Aat the second outlet 315. In some embodiments of the present disclosure,the first tubular body 302 is at least partially cylindrical in shape.As used herein, “at least partially cylindrical in shape” is used torefer to a body which is cylindrical in shape along at least a portionof its length. For example, in some embodiments, the first tubular body302 is at least partially cylindrical in shape if one or more of thefirst inlet 303 and the first outlet 305 are cylindrical in shape. Insome embodiments of the present disclosure, the first tubular body 302is at least partially conical in shape. As used herein, “at leastpartially conical in shape” is used to refer to a body which is conicalin shape along at least a portion of its length, and includes bodieswhich do not form complete cones. For example, in some embodiments, thefirst tubular body 302 is at least partially conical in shape when thefirst tubular body 302 narrows in internal diameter from the first inlet303 toward the first 305, forming a partial cone. In some embodiments ofthe present disclosure, the second tubular body 311 is substantiallycylindrical in shape. In some embodiments of the present disclosure, thesecond tubular body 311 is substantially conical in shape. In otherembodiments, either the first tubular body 302 or the second tubularbody 311 can be non-cylindrical in shape (e.g., they have a non-circularcross-section), while in further embodiments of the disclosure, both thetubular bodies 302 and 311 can be non-cylindrical in shape.

In some embodiments, the first inlet can be a solid fines inlet and thesecond inlet can be a motive gas inlet. Alternatively, the first inletof the eductor can be a motive gas inlet and the second inlet can be asolid fines inlet. In embodiments, the second outlet 315 can furthercomprise a nozzle in the mixing chamber. Thus, the second outlet canfurther comprise a nozzle in the mixing chamber regardless of whetherthe second outlet is a motive gas outlet or a solid fines outlet.Typically, the first inlet of the eductor is a solid fines inlet and thesecond inlet is a motive gas inlet and the second outlet of the eductorfurther comprises a nozzle in the mixing chamber.

According to a further aspect, the eductor according to this disclosurecan further comprise a converging-diverging nozzle adjacent to the firstoutlet. In this aspect, the eductor uses a converging (inlet) nozzle anddiverging (outlet) diffuser (“converging-diverging nozzle”) and thepressure energy of a motive fluid, typically a motive gas, to create alow pressure zone to suction and entrain another fluid. The reduction influid pressure results when a fluid flows through a section of a pipethat first narrows or constricts to a smaller cross section and thenenlarges to a larger cross section. In some embodiments of the presentdisclosure, the eductor 301 further includes exit piping downstream ofthe first outlet which is not substantially parallel with the centralaxis A of the first tubular body 302. In some embodiments of the presentdisclosure, the eductor 301 further includes exit piping downstream ofthe first outlet which is not substantially parallel with the centralaxis A of the first tubular body 302.

As shown in FIG. 4, and in contrast to the CFD simulation of FIG. 2, theeductor of FIG. 3 does not experience any problematic low flow areaswhich may lead to the fouling or accumulation of fines. FIG. 4 shows acomputational fluid dynamics simulation model of the eductor of FIG. 3,wherein the eductor of FIG. 3 is configured such that a stream of finesis introduced through the first inlet 303 and a motive gas is introducedthrough the second inlet 313, and is injected into the mixing chamber309 through a second outlet 315, such that a combined stream ofentrained fines in a motive gas exits the eductor through the firstoutlet 305. In some embodiments of the present disclosure, a stream offines may be introduced through the first inlet 303 at a rate of about2,000 lbs/hr. Arrows within the eductor 301 indicate the direction offlow, while the color of the arrows indicates the magnitude or velocityof the flow, according to the color scale illustrated in the figure. Ascan be seen by reference to the model in this figure, the design ofeductor 301 results in now low flow areas, and thus would result inlower, reduced, minimized or no fouling or clogging of the eductor withpolymer fines, depending upon the operating conditions of the productionsystem in which the eductor 301 is installed. As would be understood byone of skill in the art, this eductor design will not result in any lowflow areas even if the fines stream is introduced through the secondinlet 313 and a motive gas is introduced through the first inlet 303.

FIG. 5 illustrates a schematic diagram of an apparatus and process forpolymerizing olefins, employing the eductor of FIG. 3. In thisprocess/apparatus, a stream of olefins 505 is introduced to apolymerization reactor 503. The stream of olefins 505 can include anysuitable olefin, combination of olefins, and in some embodiments mayinclude further components such as catalysts, polymerization initiators,chain length controlling agents, and the like, as would be understoodthe skilled person. The stream of olefins 505 is then at least partiallypolymerized in the polymerization reactor 503. A stream 507 whichincludes unreacted olefins and fine polymer solids exits thepolymerization reactor 503, and travels to a cyclone 509, where it isseparated into a gas stream 511 and a stream of solid fines 513. In someembodiments, the stream of unreacted olefins and fine polymer solids 507may also contain other components, such as hydrocarbons, catalysts,initiators, and the like, as described herein. The stream of solid fines513 is then introduced to an eductor 301 along with a stream of a motivegas 515. In embodiments, the inlet of eductor 301 is immediatelyadjacent the solids outlet at the bottom of the cyclone, but this is notnecessary. In some embodiments of FIG. 5, the motive gas 515 can includeall or a portion of the gas stream 511. For example, as shown in FIG. 5,the motive gas 515 may consist of the gas stream 511 which has beenpassed through a first heat exchanger 519 and a compressor 521. Anyportion of the gas stream 511 which is not used as motive gas 511 maythen be passed through a second heat exchanger 523 and recycled back tothe polymerization reactor 503. A stream of entrained solid fines 517exits the eductor, and is recycled back to the polymerization reactor503. As shown in FIG. 5, a stream of polymer product 525 exits thepolymerization reactor 503.

While eductor 301 is depicted as showing a stream of fines 513 enteringthrough the top of eductor 301 and a stream of entrained solid fines 517exiting through the bottom of the eductor 301, it should be understoodthat the eductor 301 may have any suitable configuration, as discussedin reference to FIG. 3. For example, in some embodiments, the eductor301 may be configured such that the stream of fines 513 enters throughthe side of eductor 301 and a stream of entrained solid fines 517 exitsthrough the side of the eductor 301, while in some embodiments theeductor 301 may be configured such that the stream of fines 513 entersthrough the side of eductor 301 and a stream of entrained solid fines517 exits through the bottom of the eductor 301. In still yet otherembodiments, the eductor 301 may be configured such that the stream offines 513 enters through a side of eductor 301 and a stream of entrainedsolid fines 517 exits through an opposite side of the eductor 301.

FIG. 6 illustrates a converging-diverging nozzle 601 which can besituated adjacent to the first outlet 305 of an eductor 301. Theconverging-diverging nozzle 601 has a converging inlet nozzle 603 and adiverging outlet diffuser 605. The converging-diverging nozzle 601 thususes the pressure energy of a motive gas to create a low pressure zoneto suction and entrain another fluid. For example, theconverging-diverging nozzle 601 may be used to enhance the suctionapplied to the fines stream, or to suction and entrain another fluid,different from the fluid which was entrained by the eductor 301.

The eductor, process and apparatus of this disclosure are applicable toany gas phase reaction process in which solid fines are produced. Forexample, any suitable olefin or combination of olefins may be used inthe stream of olefins 505, for example, those containing from 2 to 16carbon atoms. The olefins can be polymerized to form homopolymers,copolymers, terpolymers, and the like. In some embodiments,polyethylenes may be prepared. Such polyethylenes include homopolymersof ethylene and copolymers of ethylene and at least one alpha-olefinwherein the ethylene content is at least about 50% by weight of thetotal monomers involved. Exemplary alpha-olefins that may be utilizedare propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene,4-methyl-1-pentene, 1-decene, 1-dodecene, 1-hexadecene and the like.Also utilizable herein are polyenes such as 1,3-hexadiene,1,4-hexadiene, 1,5-hexadiene, cyclopentadiene, dicyclopentadiene,4-vinylcyclohex-1-ene, 1,5-cyclooctadiene, 5-vinylidene-2-norbornene,5-vinyl-2-norbornene, and olefins formed in situ in the polymerizationmedium. When olefins are formed in situ in the polymerization medium,the formation of polyethylenes containing long chain branching mayoccur.

In the present disclosure, any catalyst suitable for polymerizingolefins may be used. For example, an olefin polymerization catalyst mayinclude at least one metal selected from Groups 3, 4, 5, 6, 7, 8, 9, 10,11, 12 and 13 of the Periodic Table of the Elements. Exemplary metalsare titanium, zirconium, hafnium, scandium, vanadium, iron, chromium,nickel and aluminum. The olefin polymerization catalyst may be neutralor cationic.

Examples of such polymerization catalysts include, but are not limitedto:

-   -   [1] catalyst compounds and compositions containing a Group 6        element, such as chromium, examples of which include but are not        limited to the chromium oxide-based catalysts and the        organochromium catalysts which may be supported and/or        activated;    -   [2] Ziegler-Natta catalysts and compositions of all types, which        typically contain a transition metal component and a co-catalyst        such as an organoaluminum compound;    -   [3] Metallocene catalysts of all types, which is used herein to        refer to the substituted and unsubstituted transition metal        mono(cyclopentadienyl) and bis(cyclopentadienyl) based        catalysts, and analogs of such compounds, such as pentadienyl,        pyrrole, boratabenzene, and the like, typically also including        an organometallic co-catalyst such as an aluminoxane (such as        methyl aluminoxane), alkyl or aryl aluminum compound, or alkyl        or aryl substituted boron compound;    -   [4] Any catalyst compound containing a Group 13 element, such as        aluminum containing compounds;    -   [5] Catalyst compounds and compositions containing a Group 10        element, for example, a nickel containing catalyst such as        cationic nickel alkyl diimine complexes, often used in        combination with an organometallic co-catalyst;    -   [6] Catalyst compounds and compositions containing a Group 8        element, such as iron containing compounds, which also        optionally may include an organometallic co-catalyst such as an        alkylaluminoxane or other organoaluminum or organoboron        compound;    -   [7] Any compound containing a Group 4 element, such as titanium        and zirconium containing compounds, examples of which include        cationic or neutral titanium and zirconium compounds, and also        which may include an organometallic co-catalyst such as an        alkylaluminoxane or other organoaluminum or organoboron        compound; and    -   [8] An olefin polymerization catalyst that polymerizes olefins        to produce interpolymers of olefins having a molecular weight        distribution (MWD) of from 1 to 2.5.

In some embodiments, the above catalysts can be supported on any varietyof particulate carriers, as known in the art.

Any suitable polymerization reactor 503 may be used in the presentdisclosure. For example, the polymerization reactor 503 may be afluidized bed reactor for polymerizing olefins. Typically, such afluidized bed reactor includes a reaction zone and a so-called “velocityreduction zone.” The reaction zone can include a bed of growing polymerparticles, formed polymer particles, and a minor amount of catalystparticles fluidized by a continuous flow of gaseous monomer and diluent(condensate) to remove heat of polymerization from the reaction zone. Asuitable rate of gas flow may be readily determined by simpleexperiment. The velocity-reduction zone (also referred to as a“disengagement chamber”) can include an area located above the reactionzone and having a relatively large cross-sectional area, larger than thecross-sectional area of the reaction zone, and with a sufficient heightto minimize intensive entrainment of solid particles out of the reactionfluidized bed reactor. In some embodiments, the reaction zone may havean exemplary height-to-diameter ratio of 3-7.5 and the disengagementzone may have an exemplary height-to-diameter ratio of about 1-2. A gasphase reactor 12 having other height-to-diameter ratios for the reactionzone and disengagement zone may be employed. The particular dimensionsof the reactor zone and disengagement zone may impact residence time inthe fluidized bed reactor.

In accordance with embodiments of the present disclosure, thepolymerization in the polymerization reactor 503 can be carried out at apressure of about 0.5 MPa to about 5 MPa, and at a temperature of fromabout 30° C. to about 150° C. The gas mixture passing through thefluidized bed polymerization reactor can contain, among the olefin(s) tobe polymerized, dienes, hydrogen, and a gas that is inert towards thecatalyst such as nitrogen, methane, ethane, n-pentane, iso-pentane,molecules comprising 2, 3, 4, 5, 6, 7, or 8 carbon atoms, and/orpropane. In some embodiments of the present disclosure, the gas mixturecan pass through the fluidized bed as a rising stream, with afluidization velocity that is generally between 2 and 8 times theminimum fluidization velocity, e.g., between about 0.2 m/s and about 1.6m/s. In embodiments of the present invention, fluidization conditionscan include, but are not limited to, any of the following regimes:particulate bubbling, slug flow, turbulent, fast fluidization, orpneumatic conveying.

Embodiments

The invention is described above with reference to numerous aspects andembodiments, and specific examples. Many variations will suggestthemselves to those skilled in the art in light of the above detaileddescription. All such obvious variations are within the full intendedscope of the appended claims. Other embodiments of the invention caninclude, but are not limited to, the following (embodiments typicallyare described as “comprising” but, alternatively, can “consistessentially of” or “consist of” unless specifically stated otherwise)

-   1. An eductor comprising:    -   a first tubular body having a hollow interior and comprising        -   a first inlet and a first outlet spaced apart from the first            inlet along a central axis, and        -   a sidewall circumscribing the central axis and defining a            mixing chamber; and    -   a second tubular body having a hollow interior and comprising a        second inlet and a spaced apart second outlet wherein the second        tubular body extends into the mixing chamber through the        sidewall of the first tubular body between the first inlet and        the first outlet,    -   wherein the second inlet is oriented substantially perpendicular        to the axis of the first tubular body,    -   wherein the second tubular body comprises a first bend of less        than 90° from perpendicular toward the first outlet before        extending into the mixing chamber, and    -   wherein the second tubular body comprises a second bend of less        than 90° toward the first outlet after extending into the mixing        chamber.-   2. The eductor of embodiment 1, wherein the second tubular body    makes a first bend of about 45° from perpendicular toward the first    outlet before entering the mixing chamber and a second bend of about    45° toward the first outlet after entering the mixing chamber.-   3. The eductor of embodiment 1, wherein the second tubular body is    substantially parallel to the central axis at the second outlet.-   4. The eductor of embodiment 1, wherein the first inlet is a solid    fines inlet and the second inlet is a motive gas inlet.-   5. The eductor of embodiment 4, wherein the second outlet further    comprises a nozzle in the mixing chamber.-   6. The eductor of embodiment 1, wherein the first inlet is a motive    gas inlet and the second inlet is a solid fines inlet.-   7. The eductor of embodiment 1, wherein the first tubular body and    the second tubular body below the second bend after entering the    mixing chamber are coaxial.-   8. The eductor of embodiment 1, wherein the first tubular body and    the second tubular body below the second bend after entering the    mixing chamber are not coaxial.-   9. The eductor of embodiment 1, wherein the first tubular body is at    least partially cylindrical in shape.-   10. The eductor of embodiment 1, wherein the second tubular body is    at least partially cylindrical in shape.-   11. The eductor of embodiment 1, wherein the first tubular body is    at least partially conical in shape.-   12. The eductor of embodiment 1, further comprising exit piping    downstream of the first outlet which is not parallel with the axis    of the first tubular body.-   13. The eductor of embodiment 1, further comprising a    converging-diverging nozzle adjacent to the first outlet.-   14. An eductor comprising:    -   a first tubular body having a hollow interior and comprising        -   a first inlet and a first outlet spaced apart from the first            inlet along a central axis, and        -   a sidewall circumscribing the central axis and defining a            mixing chamber; and    -   a second tubular body having a hollow interior and comprising a        second inlet and a spaced apart second outlet, wherein the        second tubular body extends into the mixing chamber through the        sidewall of the first tubular body between the first inlet and        the first outlet, and    -   wherein the second tubular body comprises a bend of less than        90° toward the first outlet after extending into the mixing        chamber.-   15. An eductor comprising:    -   a first tubular body having a hollow interior and comprising        -   a first inlet and a first outlet spaced apart from the first            inlet along a central axis, and        -   a sidewall circumscribing the central axis and defining a            mixing chamber; and    -   a second tubular body having a hollow interior and comprising a        second inlet and a spaced apart second outlet, wherein the        second tubular body extends into the mixing chamber through the        sidewall of the first tubular body between the first inlet and        the first outlet,    -   wherein the second inlet is oriented at an angle less than        perpendicular to the axis of the first tubular body toward the        first outlet before extending into the mixing chamber, and    -   wherein the second tubular body comprises a bend at an angle        less than perpendicular toward the first outlet after extending        into the mixing chamber.-   16. A method of motivating a gas stream containing solid fines    comprising the steps of:    -   introducing a gas stream comprising solid fines and a gas stream        comprising a motive gas into an eductor, wherein the eductor        comprises:        -   a first tubular body having a hollow interior and comprising        -   a first inlet and a first outlet spaced apart from the first            inlet along a central axis, and        -   a sidewall circumscribing the central axis and defining a            mixing chamber;    -   a second tubular body having a hollow interior and comprising a        second inlet and a spaced apart second outlet, wherein the        second tubular body extends into the mixing chamber through the        sidewall of the first tubular body between the first inlet and        the first outlet,    -   wherein the second inlet is oriented substantially perpendicular        to the axis of the first tubular body,    -   wherein the second tubular body comprises a first bend of less        than 90° from perpendicular toward the first outlet before        extending into the mixing chamber, and    -   wherein the second tubular body comprises a second bend of less        than 90° toward the first outlet after extending into the mixing        chamber.-   17. The method according to embodiment 16, wherein the second    tubular body makes a first bend of about 45° from perpendicular    toward the first outlet before extending into the mixing chamber and    a second bend of about 45° toward the first outlet after extending    into the mixing chamber.-   18. The method according to embodiment 16, wherein the first inlet    is a solid fines inlet and the second inlet is a motive gas inlet.-   19. The method according to embodiment 18, wherein the second outlet    further comprises a nozzle in the mixing chamber.-   20. The method according to embodiment 16, wherein the first inlet    is a motive gas inlet and the second inlet is a solid fines inlet.-   21. The method according to embodiment 16, wherein the first tubular    body and the second tubular body below the second bend after    extending into the mixing chamber are coaxial.-   22. The method according to embodiment 16, wherein the first tubular    body and the second tubular body below the second bend after    extending the mixing chamber are not coaxial.-   23. The method according to embodiment 16, wherein one or both of    the first tubular body and the second tubular body is at least    partially cylindrical in shape.-   24. The method according to embodiment 16, wherein the first tubular    body is at least partially conical in shape.-   25. The method according to embodiment 16, further comprises exit    piping downstream of the first outlet of the eductor which is not    parallel with the axis of the first tubular body.-   26. The method according to embodiment 16, wherein the eductor    further comprises a converging-diverging nozzle adjacent to the    first outlet.-   27. An apparatus for polymerizing olefins, comprising:    -   a polymerization reactor for contacting one or more olefins with        a catalyst under polymerization conditions to form a gas stream        comprising solid fines and unreacted olefins;    -   a fines separator in fluid communication with the polymerization        reactor for separating the solid fines from the unreacted        olefins; and    -   an eductor in fluid communication with the fines separator for        conveying the solid fines back to the polymerization reactor,        wherein the eductor comprises:    -   a first tubular body having a hollow interior and comprising        -   a first inlet and a first outlet spaced apart from the first            inlet along a central axis, and        -   a sidewall circumscribing the central axis and defining a            mixing chamber; and    -   a second tubular body having a hollow interior and comprising a        second inlet and a spaced apart second outlet, wherein the        second tubular body extends into the mixing chamber through the        sidewall of the first tubular body between the first inlet and        the first outlet,    -   wherein the second inlet is oriented substantially perpendicular        to the axis of the first tubular body,    -   wherein the second tubular body comprises a first bend of less        than 90° from perpendicular toward the first outlet before        extending into the mixing chamber, and    -   wherein the second tubular body comprises a second bend of less        than 90° toward the first outlet after extending into the mixing        chamber.-   28. The apparatus of embodiment 27, further comprising a heat    exchanger for cooling the unreacted olefins from the fines    separator, a compressor for compressing the cooled unreacted    olefins, and a conduit for recycling the cooled and compressed    unreacted olefins back to the polymerization reactor.-   29. The apparatus of embodiment 27, wherein the gas stream further    comprises an inert hydrocarbon.-   30. The apparatus of embodiment 27, further comprising a conduit for    conveying at least a portion of the cooled and compressed unreacted    olefins as a motive gas to the first inlet or the second inlet of    the eductor.-   31. The apparatus of embodiment 27, wherein the first inlet is a    solid fines inlet and the second inlet is a motive gas inlet.-   32. The apparatus of embodiment 31, wherein the second outlet    further comprises a nozzle in the mixing chamber.-   33. The apparatus of embodiment 27, wherein the first inlet is a    motive gas inlet and the second inlet is a solid fines inlet.-   34. The apparatus of embodiment 27, wherein the first tubular body    and the second tubular body below the second bend after entering the    mixing chamber are coaxial.-   35. The apparatus of embodiment 27, wherein the first tubular body    and the second tubular body below the second bend after entering the    mixing chamber are not coaxial.-   36. The apparatus of embodiment 27, wherein one or both of the first    tubular body and the second tubular body is at least partially    cylindrical in shape.-   37. The apparatus of embodiment 27, wherein the first tubular body    is at least partially conical in shape.-   38. The apparatus of embodiment 27, wherein the eductor further    comprises a converging-diverging nozzle adjacent to the first    outlet.-   39. A process for polymerizing olefins comprising:    -   contacting one or more olefins with a catalyst in a        polymerization reactor under polymerization conditions to form a        gas stream comprising fine polymer particles and unreacted        olefins;    -   passing the gas stream to a fines separator to separate the fine        polymer particles from the unreacted olefins;    -   passing the fine polymer particles from the fines separator to        the eductor of embodiment 1; and    -   introducing a motive gas into the eductor to convey the fine        polymer particles back to the polymerization reactor.-   40. The process of embodiment 39, further comprising passing the    unreacted olefins from the fines separator to a heat exchanger to    cool the unreacted olefins, passing the cooled unreacted olefins to    a compressor to compress the cooled unreacted olefins, and    introducing the cooled and compressed unreacted olefins back to the    polymerization reactor.-   41. The process of embodiment 39, wherein the motive gas comprises    at least a portion of the cooled and compressed unreacted olefins.-   42. The process of embodiment 39, wherein the first inlet is a solid    fines inlet and the second inlet is a motive gas inlet.-   43. The process of embodiment 42, wherein the second outlet further    comprises a nozzle in the mixing chamber.-   44. The process of embodiment 39, wherein the first inlet is a    motive gas inlet and the second inlet is a solid fines inlet.-   45. The process of embodiment 39, wherein the first tubular body and    the second tubular body below the second bend after entering the    mixing chamber are coaxial.-   46. The process of embodiment 39, wherein the first tubular body and    the second tubular body below the second bend after entering the    mixing chamber are not coaxial.-   47. The process of embodiment 39, wherein one or both of the first    tubular body and the second tubular body is at least partially    cylindrical in shape.-   48. The process of embodiment 39, wherein the first tubular body is    at least partially conical in shape.-   49. The process of embodiment 39, wherein the eductor further    comprises a converging-diverging nozzle adjacent to the first    outlet.

What is claimed is:
 1. An eductor comprising: a first tubular bodyhaving a hollow interior and comprising a first inlet and a first outletspaced apart from the first inlet along a central axis, and a sidewallcircumscribing the central axis and defining a mixing chamber; and asecond tubular body having a hollow interior and comprising a secondinlet and a spaced apart second outlet wherein the second tubular bodyextends into the mixing chamber through the sidewall of the firsttubular body between the first inlet and the first outlet, wherein thesecond inlet is oriented substantially perpendicular to the axis of thefirst tubular body, wherein the second tubular body comprises a firstbend of less than 90° from perpendicular toward the first outlet beforeextending into the mixing chamber, and wherein the second tubular bodycomprises a second bend of less than 90° toward the first outlet afterextending into the mixing chamber.
 2. The eductor of claim 1, whereinthe second tubular body makes a first bend of about 45° fromperpendicular toward the first outlet before entering the mixing chamberand a second bend of about 45° toward the first outlet after enteringthe mixing chamber.
 3. The eductor of claim 1, wherein the secondtubular body is substantially parallel to the central axis at the secondoutlet.
 4. The eductor of claim 1, wherein the first inlet is a solidfines inlet and the second inlet is a motive gas inlet.
 5. The eductorof claim 1, wherein the first inlet is a motive gas inlet and the secondinlet is a solid fines inlet.
 6. The eductor of claim 1, wherein thefirst tubular body and the second tubular body below the second bendafter entering the mixing chamber are coaxial.
 7. The eductor of claim1, wherein one or more of the first tubular body and the second tubularbody are at least partially cylindrical in shape.
 8. The eductor ofclaim 1, wherein the first tubular body is at least partially conical inshape.
 9. The eductor of claim 1, further comprising aconverging-diverging nozzle adjacent to the first outlet.
 10. A methodof motivating a gas stream containing solid fines comprising the stepsof: introducing a gas stream comprising solid fines and a gas streamcomprising a motive gas into an eductor, wherein the eductor comprises:a first tubular body having a hollow interior and comprising a firstinlet and a first outlet spaced apart from the first inlet along acentral axis, and a sidewall circumscribing the central axis anddefining a mixing chamber; a second tubular body having a hollowinterior and comprising a second inlet and a spaced apart second outlet,wherein the second tubular body extends into the mixing chamber throughthe sidewall of the first tubular body between the first inlet and thefirst outlet; and wherein the second inlet is oriented substantiallyperpendicular to the axis of the first tubular body, wherein the secondtubular body comprises a first bend of less than 90° from perpendiculartoward the first outlet before extending into the mixing chamber, andwherein the second tubular body comprises a second bend of less than 90°toward the first outlet after extending into the mixing chamber.
 11. Themethod according to claim 10, wherein the second tubular body makes afirst bend of about 45° from perpendicular toward the first outletbefore extending into the mixing chamber and a second bend of about 45°toward the first outlet after extending into the mixing chamber.
 12. Themethod according to claim 10, wherein the first inlet is a solid finesinlet and the second inlet is a motive gas inlet.
 13. The methodaccording to claim 10, wherein the first inlet is a motive gas inlet andthe second inlet is a solid fines inlet.
 14. The method according toclaim 10, wherein the first tubular body and the second tubular bodybelow the second bend after extending into the mixing chamber arecoaxial.
 15. The method according to claim 10, wherein one or both ofthe first tubular body and the second tubular body is at least partiallycylindrical in shape.
 16. The method according to claim 10, wherein thefirst tubular body is at least partially conical in shape.
 17. Themethod according to claim 10, wherein the eductor further comprises aconverging-diverging nozzle adjacent to the first outlet.
 18. Anapparatus for polymerizing olefins, comprising: a polymerization reactorfor contacting one or more olefins with a catalyst under polymerizationconditions to form a gas stream comprising solid fines and unreactedolefins; a fines separator in fluid communication with thepolymerization reactor for separating the solid fines from the unreactedolefins; and an eductor in fluid communication with the fines separatorfor conveying the solid fines back to the polymerization reactor,wherein the eductor comprises: a first tubular body having a hollowinterior and comprising a first inlet and a first outlet spaced apartfrom the first inlet along a central axis, and a sidewall circumscribingthe central axis and defining a mixing chamber; and a second tubularbody having a hollow interior and comprising a second inlet and a spacedapart second outlet, wherein the second tubular body extends into themixing chamber through the sidewall of the first tubular body betweenthe first inlet and the first outlet, wherein the second inlet isoriented substantially perpendicular to the axis of the first tubularbody, wherein the second tubular body comprises a first bend of lessthan 90° from perpendicular toward the first outlet before extendinginto the mixing chamber, and wherein the second tubular body comprises asecond bend of less than 90° toward the first outlet after extendinginto the mixing chamber.
 19. The apparatus of claim 18, furthercomprising a heat exchanger for cooling the unreacted olefins from thefines separator, a compressor for compressing the cooled unreactedolefins, and a conduit for recycling the cooled and compressed unreactedolefins back to the polymerization reactor.
 20. The apparatus of claim18, wherein the gas stream further comprises an inert hydrocarbon. 21.The apparatus of claim 18, further comprising a conduit for conveying atleast a portion of the cooled and compressed unreacted olefins as amotive gas to the first inlet or the second inlet of the eductor. 22.The apparatus of claim 18, wherein the first inlet is a solid finesinlet and the second inlet is a motive gas inlet.
 23. The apparatus ofclaim 18, wherein the first inlet is a motive gas inlet and the secondinlet is a solid fines inlet.
 24. The apparatus of claim 18, wherein thefirst tubular body and the second tubular body below the second bendafter entering the mixing chamber are coaxial.
 25. The apparatus ofclaim 18, wherein one or both of the first tubular body and the secondtubular body is at least partially cylindrical in shape.
 26. Theapparatus of claim 18, wherein the first tubular body is at leastpartially conical in shape.
 27. The apparatus of claim 18, wherein theeductor further comprises a converging-diverging nozzle adjacent to thefirst outlet.
 28. A process for polymerizing olefins comprising:contacting one or more olefins with a catalyst in a polymerizationreactor under polymerization conditions to form a gas stream comprisingfine polymer particles and unreacted olefins; passing the gas stream toa fines separator to separate the fine polymer particles from theunreacted olefins; passing the fine polymer particles from the finesseparator to the eductor of claim 1; and introducing a motive gas intothe eductor to convey the fine polymer particles back to thepolymerization reactor.